YAMAHA YZ250F 2015 Owners Manual

CLUTCH
5-38
EAS1SM5234REMOVING THE CLUTCH
1. Remove:
• Clutch boss nut “1”
• Lock washer “2”
• Clutch boss “3”
TIP
• Straighten the lock washer tab.
• While holding the clutch boss with the clutch
holder “4”, loosen the clutch boss nut.
EAS1SM5235CHECKING THE FRICTION PLATES
1. Check:
• Friction plate
Damage/wear  Replace the friction plates
as a set.
2. Measure:
• Friction plate thickness
Out of specification  Replace the friction
plates as a set.
TIP
Measure it at four points on the friction plate.
EAS1SM5236
CHECKING THE CLUTCH PLATES
1. Check:
• Clutch plate
Damage  Replace the clutch plates as a
set.
2. Measure:
• Clutch plate warpage
(with a surface plate and thickness gauge
“1”)
Out of specification  Replace the clutch
plates as a set.
EAS1SM5237CHECKING THE CLUTCH SPRINGS
1. Check:
• Clutch spring
Damage  Replace the clutch springs as a
set.
2. Measure:
• Clutch spring free length
Out of specification  Replace the clutch
springs as a set. Clutch holder
90890-04086
YM-91042
Friction plate thickness
2.90–3.10 mm (0.114–0.122 in)
Wear limit
2.85 mm (0.112 in)
34
12
Warpage limit
0.10 mm (0.0039 in)
Clutch spring free length
45.00 mm (1.77 in)
Limit
44.00 mm (1.73 in)

CLUTCH
5-39
EAS1SM5238CHECKING THE CLUTCH HOUSING
1. Check:
• Clutch housing dogs “a”
Damage/pitting/wear  Deburr the clutch
housing dogs or replace the clutch housing.
TIP
Pitting on the clutch housing dogs will cause er-
ratic clutch operation.
EAS1SM5239CHECKING THE CLUTCH BOSS
1. Check:
• Clutch boss splines
Damage/pitting/wear  Replace the clutch
boss.
TIP
Pitting on the clutch boss splines will cause er-
ratic clutch operation.
EAS1SM5240CHECKING THE PRESSURE PLATE
1. Check:
• Pressure plate
Crack/damage  Replace.
EAS1SM5241
CHECKING THE PUSH LEVER SHAFT
1. Check:
• Push lever shaft
Wear/damage  Replace.
EAS1SM5242CHECKING THE CLUTCH PUSH RODS
1. Check:
• Push rod 1 “1”
• Bearing “2”
• Washer “3”
• Push rod 2 “4”
•Ball “5”
Cracks/damage/wear  Replace.
2. Measure:
• Push rod 2 bending limit
Out of specification  Replace.
EAS1SM5243CHECKING THE PRIMARY DRIVE GEAR
1. Check:
• Primary drive gear
Damage/wear  Replace the primary drive
and primary driven gears as a set.
Excessive noise during operation  Re-
place the primary drive and primary driven
gears as a set.
2. Check:
• Primary-drive-gear-to-primary-driven-gear
free play
Free play exists  Replace the primary
drive and primary driven gears as a set.
a
Push rod bending limit
0.10 mm (0.0039 in)

CLUTCH
5-40
EAS1SM5244CHECKING THE PRIMARY DRIVEN GEAR
1. Check:
• Primary driven gear
Damage/wear  Replace the primary drive
and primary driven gears as a set.
Excessive noise during operation  Re-
place the primary drive and primary driven
gears as a set.
EAS1SM5245INSTALLING THE OIL SEAL
1. Install:
• Oil seal “1”
• Washer “2”
• Circlip “3”
TIP
• Apply is lithium-soap-based grease on the oil
seal lip.
• Install the oil seal in parallel with its manufac-
ture's marks or numbers facing inward.
EAS1SM5246INSTALLING THE RIGHT CRANKCASE
COVER
1. Install:
• Dowel pin “1”
• O-rings “2”
• Collar “3”
• Gasket “4”
TIP
Apply the lithium-soap-based grease on the O-
ring.2. Install:
• Right crankcase cover “1”
• Right crankcase cover bolt “2”
TIP
• Apply the engine oil on the impeller shaft end.
• Mesh the impeller shaft gear “3” with primary
drive gear “4”.
• Tighten the right crankcase cover bolts in
stages and in a crisscross pattern.
New
New
3
2
1
LS
New
New
1
1 4
2
New
New
3
LS
Right crankcase cover bolt
10 Nm (1.0 m·kgf, 7.2 ft·lbf)
T R..
3
1
4
E
12

CLUTCH
5-41
EAS1SM5247INSTALLING THE CLUTCH
1. Install:
• Push lever shaft “1”
TIP
• Apply the lithium soap base grease on the oil
seal lip.
• Before installation, apply the engine oil to the
push lever shaft sliding surface.
2. Install:
• Primary driven gear “1”
• Thrust washer “2”
• Clutch boss “3”
TIP
Apply the engine oil on the primary driven gear
inner circumference.
3. Install:
• Lock washer “1”
• Clutch boss nut “2”
ECA1DX1020
NOTICE
Make sure to tighten to specification; other-
wise, it may damage the other part that is
fastened together.
TIP
Use the clutch holding tool “3” to hold the clutch
boss.4. Bend the lock washer “1” tab.
5. Install:
• Friction plate “1”
• Clutch plate “2”
• Cushion spring “3”
TIP
• Install the clutch plates and friction plates al-
ternately on the clutch boss, starting with a
friction plate and ending with a friction plate.
• Install the cushion spring “3” in the position as
shown.
• Apply the engine oil on the friction plates and
clutch plates.
Clutch boss nut
75 Nm (7.5 m·kgf, 54 ft·lbf)
1
New
T R..
Clutch holder
90890-04086
YM-91042
3
21
1
1
1
2 2
2
1
2
3

CLUTCH
5-42
6. Install:
• Bearing “1”
• Washer “2”
• Circlip “3”
To push rod 1 “4”.
TIP
Apply the engine oil on the bearing and washer.
7. Install:
• Push rod 2 “1”
•Ball “2”
• Push rod 1 “3”
TIP
Apply the engine oil on the push rod 1, 2 and
ball.
8. Install:
• Pressure plate “1”9. Install:
• Clutch spring
• Clutch spring bolt
TIP
Tighten the bolts in stages and in a crisscross
pattern.
10.Install:
• Gasket “1”
11.Install:
• Clutch cover “1”
• Clutch cover bolt
TIP
Tighten the bolts in stages and in a crisscross
pattern.
NewClutch spring bolt
10 Nm (1.0 m·kgf, 7.2 ft·lbf)
Clutch cover bolt
10 Nm (1.0 m·kgf, 7.2 ft·lbf)
T R..
1
2 3
45
New
T R..
1

CLUTCH
5-43
EAS1SM5248INSTALLING THE KICKSTARTER LEVER
1. Install:
• Kickstarter lever “1”
• Washers
• Bolt (kickstarter lever)
TIP
Install so that there is a clearance “a” of 5 mm
(0.2 in) or more between the kickstarter lever
and the frame and that the kickstarter lever
does not contact the right crankcase cover
when it is pulled.Bolt (kickstarter lever)
33 Nm (3.3 m·kgf, 24 ft·lbf)
T R..
1
a

KICKSTATER
5-44
EAS1SM5249
KICKSTATER
Removing the kick shaft
Order Part name Q’ty Remarks
Primary driven gear Refer to “CLUTCH” on page 5-35.
1 Kick idle gear 1
2 Kick shaft assembly 1
3 Spring guide 1
4 Torsion spring 1
5 Ratchet wheel 1
6 Kick gear 1
7 Kick shaft 1
For installation, reverse the removal proce-
dure.

KICKSTATER
5-45
EAS1SM5250REMOVING THE KICK SHAFT ASSEMBLY
1. Remove:
• Kick shaft assembly “1”
TIP
Unhook the torsion spring “2” from the hole “a”
in the crankcase.
EAS1SM5251CHECKING THE KICK SHAFT AND RATCH-
ET WHEEL
1. Check:
• Ratchet wheel “1” smooth movement
Unsmooth movement  Replace.
• Kick shaft “2”
Wear/damage  Replace the kick shaft as-
sembly.
• Spring “3”
Broken  Replace.
EAS1SM5252CHECKING THE KICK GEAR, KICK IDLE
GEAR AND RATCHET WHEEL
1. Check:
• Kick gear “1”
Wear/damage  Replace the kick shaft as-
sembly.
• Kick idle gear “2”
• Ratchet wheel “3”
• Gear teeth “a”
• Ratchet teeth “b”
Wear/damage  Replace.
EAS1SM5253INSTALLING THE KICK SHAFT ASSEMBLY
1. Install:
• Kick gear “1”
• Washer “2”
• Circlip “3”
• Ratchet wheel “4”
• Spring “5”
• Washer “6”
• Circlip “7”
(to the kick shaft “8”)
TIP
• Apply molybdenum disulfide oil to the inner
circumferences of the kick gear and ratchet
wheel.
• Align the punch mark “a” on the ratchet wheel
with the punch mark “b” on the kick shaft.
2. Install:
• Torsion spring “1”
(to the kick shaft “2”)
TIP
Make sure the stopper “a” of the torsion spring
fits into the hole “b” on the kick shaft.
31
2
a
b
3
12
New
New

KICKSTATER
5-46
3. Install:
• Spring guide “1”
TIP
Slide the spring guide into the kick shaft, make
sure the groove “a” in the spring guide fits on
the stopper of the torsion spring.
4. Install:
• Kick shaft assembly “1”
TIP
• Before installation, apply molybdenum disul-
fide grease to the contacting surfaces of the
kick shaft ratchet wheel guide “2” and the kick
shaft stopper “a”.
• Apply the engine oil on the kick shaft.
• Slide the kick shaft assembly into the crank-
case and make sure the kick shaft stopper “a”
fits into the kick shaft ratchet wheel guide.5. Install:
• Torsion spring “1”
TIP
Turn the torsion spring clockwise and hook into
the proper hole “a” in the crankcase.
EAS1SM5254INSTALLING THE KICK IDLE GEAR
1. Install:
• Kick idle gear “1”
• Washer “2”
• Circlip “3”
TIP
• Apply the engine oil on the kick idle gear inner
circumference.
• Install the kick idle gear with its depressed
side “a” toward you.
1 2a b
New

SHIFT SHAFT
5-47
EAS1SM5255
SHIFT SHAFT
Removing the shift shaft and stopper lever
Order Part name Q’ty Remarks
Primary driven gear Refer to “CLUTCH” on page 5-35.
1 Shift pedal 1
2 Shift shaft 1
3Oil seals 1
4Collars 1
5 Shift shaft spring 1
6Roller 1
7 Shift guide 1
8 Shift lever assembly 1
9 Shift lever 1
10 Pawl 2
11 Pawl pin 2
12 Spring 2
13 Stopper lever 1
LS
1 3
10 Nm (1.0 m kgf, 7.2 ft lbf)
13
15 14
10 Nm (1.0 m kgf, 7.2 ft lbf)
30 Nm (3.0 m kgf, 22 ft lbf)
LT
610 11 12
118
1210
4
25
LT
7
LT
E
12 Nm (1.2 mkgf, 8.7 ftIbf)T.R.E